Operating Activities
The ability to generate cash from operating activities is one of the Company’s fundamental financial strengths. Net cash provided by operating activities from continuing operations (“Operating Cash Flow”) was $732.0 in the first six months of 2021 compared to $752.4 in the first six months of 2020. The decrease in Operating Cash Flow for the first six months of 2021 compared to the first six months of 2020 is primarily due to a higher usage of cash related to the change in working capital, partially offset by an increase in net income from continuing operations.
In the first six months of 2021, the components of working capital as presented on the accompanying Condensed Consolidated Statements of Cash Flow increased $194.9, excluding the impact of acquisitions and foreign currency translation, primarily due to increases in inventories of $165.4, accounts receivable of $42.4 and prepaid expenses and other current assets of $15.0 and a decrease in accrued liabilities, including income taxes, of $24.6, partially offset by an increase in accounts payable of $52.5. In the first six months of 2020, the components of working capital as presented on the accompanying Condensed Consolidated Statements of Cash Flow decreased $70.8, excluding the impact of acquisitions and foreign currency translation, primarily due to increases in accounts payable of $72.3 and accrued liabilities, including income taxes, of $34.8, along with a decrease in accounts receivable of $54.8, partially offset by increases in inventories of $69.3 and prepaid expenses and other current assets of $21.8.
The following describes the significant changes in the amounts as presented on the accompanying Condensed Consolidated Balance Sheets at June 30, 2021 as compared to December 31, 2020. Accounts receivable increased $121.2 to $2,072.8, primarily due to higher sales in the second quarter of 2021 relative to the fourth quarter of 2020, along with the impact of the MTS acquisition and the other five acquisitions (collectively, the “2021 acquisitions”) that closed during the first six months of 2021, partially offset by the effect of translation from exchange rate changes (“Translation”) at June 30, 2021 compared to December 31, 2020. Days sales outstanding at June 30, 2021 and December 31, 2020 were 71 days and 72 days, respectively. Inventories increased $309.2 to $1,771.4, primarily due to higher sales in addition to the impact of recent supply chain disruptions experienced during the first six months of 2021, along with the impact of the 2021 acquisitions, partially offset by Translation. Inventory days at June 30, 2021 and December 31, 2020 were 85 days and 79 days, respectively. Prepaid expenses and other current assets increased $33.1 to $372.0, primarily due to increases in certain prepaid expenses and other current receivables as well as the impact of the 2021 acquisitions. Property, plant and equipment, net, increased $114.7 to $1,169.3, primarily due to capital expenditures of $183.3 and the impact of the 2021 acquisitions, partially offset by depreciation of $131.6 and Translation. Goodwill increased $859.6 to $5,891.7, resulting from goodwill recognized related to the 2021 acquisitions, primarily from the MTS acquisition, partially offset by Translation. Other intangible assets, net increased $223.3 to $620.8, primarily due to the recognition of certain intangible assets related to the 2021 acquisitions, primarily from the MTS acquisition, partially offset by amortization. Other long-term assets increased $33.8 to $386.1, primarily due to an increase in operating lease right-of-use assets resulting from both leases assumed from the 2021 acquisitions as well as new and renewed lease agreements entered into during the first six months of 2021. Accounts payable increased $84.0 to $1,204.7, primarily due to increased purchasing activity related to higher sales levels, along with the impact of the 2021 acquisitions. Payable days at June 30, 2021 and December 31, 2020 were 60 days and 61 days, respectively. Total accrued expenses, including accrued income taxes, increased $88.8 to $1,042.1, primarily as a result of the MTS acquisition and the other 2021 acquisitions, along with an increase in accrued salaries and wages and other accrued expenses, partially offset by a decrease in accrued income taxes, primarily resulting from certain tax payments. Other long-term liabilities, including deferred tax liabilities, increased $140.7 to $847.0, primarily as a result of an increase in deferred tax liabilities resulting from the MTS acquisition.
There is no current requirement for cash contributions to any of the Company’s defined benefit pension plans in the U.S., and the Company plans to evaluate annually, based on actuarial calculations and the investment performance of the pension plans’ assets, the timing and amount of cash contributions in the future, as discussed in more detail in Note 10 of the Notes to Condensed Consolidated Financial Statements.
In addition to cash flow from operating activities, the Company also considers Free Cash Flow, a non-GAAP financial measure defined in the “Non-GAAP Financial Measures” section below, as a key metric in measuring the Company’s ability to generate cash. The following table reconciles Free Cash Flow to its most directly comparable U.S. GAAP financial measure for the six months ended June 30, 2021 and 2020. The decrease in Free Cash Flow was